Is there a table of sorts(like compression and octane) for how much compression works with how much quench to be pump gas friendly and still run some timing(~38*)?

I have Manley forged flattops and am not sure how far down the hole they are. I am thinking 0.010 down since they were probably made for a 3.500 crank(I have a 406). I havn't been able to find any markings other than the Manley stamp on them.

Anyway I'm looking at 0.074 quench with a 0.039 gasket and 9.8:1 compression(with a 0.025 deck and assumed piston height of 0.010 due to diff cranks). Not ideal. To get it down to 0.055 quench I'm looking at a 0.020 head gasket and about 10.3:1 static compression(8.4:1 dynamic!). On top of all this will be aluminum heads(afr 195s). Will I be ok running this combo or what should I consider something different(I'd have to use steel shims for such a thin gasket also right? Is this ok for a street/road race car)? Or am I just being anal?

This is for a street driven road race car. Weighs approx 3100lbs dry.

Not really, it is pretty much combination specific.
The tighter you can run the quench without hitting the better it normally is.
You can actually lower the compression using a thicker head gasket & cause detonation because of screwing up the quench.
There appears to be a ton of variables as I have seen engines with horrible quench run quite happily on crap gas & seen engines with good quench that rattled even though in theory they shouldn't :confused:
I would always prefer to run the quench at less than .055 if possible & preferably closer to .040.

I don't quite understand your last sentence??
Is the deck height .025 or .010?
Never assume anything,,,,, Measure it, measure it , measure it :D ;)

A shim gasket works just fine with aluminum heads. I have used them at 13.0 in circle track stuff for a season with no problems but am not positive you can get one for the large bore.
I would not modify the small bore one for your application as has been suggested a few times.
Not saying it won't work just I wouldn't try it ;)

Good subject. Mike, while you're watching this thread... What do you know about the different bore head gaskets for BBC (particularly for 454)? The gasket I'm currently using (FelPro 1017-1) has a 4.540 bore and .041 compressed height. FelPro makes a 1027 with a 4.370 bore and .039 compressed height. How would this affect compression (if ever so slightly)? I've got a 460 (4" stroke, 4.280" bore), 32cc dome pistons, 119cc heads, .010 deck. I'm getting ready to have a little more head work done and was thinking about changing gaskets when I put everything back together. I was thinking the 1027 gasket might be a better choice (tighten quench up .002 and smaller bore for a wee bit more compression).

Thoughts?

Ken - You might look at the Ferrera G50009 gasket. It's a 4.350" bore and .038" compressed. By my calculations that would increase your compression ratio about .15

We've used their gaskets on 14.9:1 small blocks with no o-rings and never had a problem.

I worked my .022" 350 SB shims over and ran them on my 406 with -461 heads!!

Like Mike says, I wouldn't do it with aluminum heads...

pdq67

Originally posted by RegaMaro:
Is there a table of sorts(like compression and octane) for how much compression works with how much quench to be pump gas friendly and still run some timing(~38*)?

I have Manley forged flattops and am not sure how far down the hole they are. I am thinking 0.010 down since they were probably made for a 3.500 crank(I have a 406). I havn't been able to find any markings other than the Manley stamp on them.

Anyway I'm looking at 0.074 quench with a 0.039 gasket and 9.8:1 compression(with a 0.025 deck and assumed piston height of 0.010 due to diff cranks). Not ideal. To get it down to 0.055 quench I'm looking at a 0.020 head gasket and about 10.3:1 static compression(8.4:1 dynamic!). On top of all this will be aluminum heads(afr 195s). Will I be ok running this combo or what should I consider something different(I'd have to use steel shims for such a thin gasket also right? Is this ok for a street/road race car)? Or am I just being anal?

This is for a street driven road race car. Weighs approx 3100lbs dry. Why do you think the pistons are for a 3.500 crank ?

What CID are you planning on ending up with ?

You mention the 406 and a 3.500 crank ..... What bore dia. ??

Originally posted by kjett:
Good subject. Mike, while you're watching this thread... What do you know about the different bore head gaskets for BBC (particularly for 454)? The gasket I'm currently using (FelPro 1017-1) has a 4.540 bore and .041 compressed height. FelPro makes a 1027 with a 4.370 bore and .039 compressed height. How would this affect compression (if ever so slightly)? I've got a 460 (4" stroke, 4.280" bore), 32cc dome pistons, 119cc heads, .010 deck. I'm getting ready to have a little more head work done and was thinking about changing gaskets when I put everything back together. I was thinking the 1027 gasket might be a better choice (tighten quench up .002 and smaller bore for a wee bit more compression).

Thoughts? =
Ken,
Sorry for the delay, I had to go play in the shop :D
What heads? A lot like the AFR with the CNC option cannot be used with the smaller gasket.
Something you want to watch.
Difference in your engine would be 10.35 10.47

Diff in gaskets is 9.59cc's (actually 9.7 according to FelPro because it ain't round) vs 10.9cc's

I use Cometic MLS for a lot of stuff & can get them in quite a few different thicknesses & bore sizes starting at .027.
Not cheap but in my opinion the very best gasket out there ;)

don't quite understand your last sentence??
Is the deck height .025 or .010?
Never assume anything,,,,, Measure it, measure it , measure it Hey Mike,
I'm not exactly sure as to what pistons I have other than that they're forged Manley flattops with valve reliefs at the moment. I looked through Manleys 2003 catalog and dont remember seeing any forged flattops for a 3.750 crank that looked similar so I assumed(yes I know bad) they're originally made for a 3.500 crank. I've heard that this will put the piston 0.010" farther down on the rod. So from that I came to a deck height of 0.025 + 0.010 = 0.035

If it'll make a difference I will go back to the machine shop and have my block decked =>0.010 down to achieve better quench. Just wondering if it's really worth it? And I was just generally curious about the whole relation of compression and quench figures. smile.gif

Why do you think the pistons are for a 3.500 crank ?

What CID are you planning on ending up with ?

You mention the 406 and a 3.500 crank ..... What bore dia. ?? Answered why I think they're for a 3.500 crank in the above reply... only assuming at the moment tho. I am using a 3.750 crank tho so I am at 406.666ci smile.gif So bore is normal at 4.155 also.

The 3.48/3.500 pistons are the same & won't work with the 3.750 stroke crank unless you are using 400 rods.
They did make a 3.75 stroke piston for both the 5.7 & 6" rod though.
Do you know what rod you have?

Originally posted by Wolfplace:

What heads? A lot like the AFR with the CNC option cannot be used with the smaller gasket.
Something you want to watch.
Difference in your engine would be 10.35 10.47

Diff in gaskets is 9.59cc's (actually 9.7 according to FelPro because it ain't round) vs 10.9cc's

I use Cometic MLS for a lot of stuff & can get them in quite a few different thicknesses & bore sizes starting at .027.
Not cheap but in my opinion the very best gasket out there ;) [/QB]Thanks, Mike. My heads are 310cc Canfield heads. Any concerns about the smaller gasket working with these heads? I guess I could call Canfield to be sure. Thanks for the tips on the Cometic gasket; that's a brand I've not heard of before
graemlins/thumbsup.gif

P.S. RegaMaro...Sorry to tread on your post. I think this kind of information is helpful to anyone trying to get max performance out of their engine.

Ken
Don't know but you can tell by setting the small gasket on the head & being sure it doesn't fall into the chamber ;)
Cometic MLS (Multi Layer Steel) or the FelPro copy is what almost all the cup guys are using now along with less well known people like Warren Johnson,,,, :D

The 3.48/3.500 pistons are the same & won't work with the 3.750 stroke crank unless you are using 400 rods.
They did make a 3.75 stroke piston for both the 5.7 & 6" rod though.
Do you know what rod you have? I am indeed using stock 400 rods and took the whole rotating assembly out of the block they came from myself. I've since had the machine shop check them and resize them. So they're at least one thing I'm sure of :D

Originally posted by RegaMaro:
</font><blockquote>quote:</font><hr />The 3.48/3.500 pistons are the same & won't work with the 3.750 stroke crank unless you are using 400 rods.
They did make a 3.75 stroke piston for both the 5.7 & 6" rod though.
Do you know what rod you have? I am indeed using stock 400 rods and took the whole rotating assembly out of the block they came from myself. I've since had the machine shop check them and resize them. So they're at least one thing I'm sure of :D </font>[/QUOTE]=
The piston has a 1.560 CH so you are in theory at 9" with your rotating parts.
With an uncut block the nominal deck is 9.025.
About the best I think you can do is the .027 Cometic + your .025 (.052 quench)without cutting the block.

email me if you need some ;)

I'll give ya a call tomorrow Mike
thx graemlins/thumbsup.gif

FYI
AFR recommends the 1027 Felpro for small bore rat motors.
Ron

Originally posted by Ron454:
FYI
AFR recommends the 1027 Felpro for small bore rat motors.
Ron =
Ron,
That is a mistake in the catalog, they do not reccommend the 1027, it will hang into the chamber.
The 1017 is the recommended gasket. ;)